1. Field of the Invention
The present invention relates to a method of communication between a mobile station and a base station in a mobile communication system, and more particularly, to a method of communication between a mobile station and a base station in a mobile communication system of IMT-2000 communication network basis, which is suitable for effective transmission of various multimedia information within a given channel capacity.
2. Background of the Invention
In general, there are bidirectional transmission and unidirectional transmission in signal transmission between a base station and a mobile station in the mobile communication system. In the bidirectional transmission, a plurality of forward time slots and backward time slots are alternatively assigned to a communication channel established between the mobile station and the base station, for transmission of data in time slot units assigned to a same time. The time slot means a time interval of information transmission on the communication channel. In the present invention, the time slot for use in information transmission from the base station to the mobile station is called as down link slot, and the time slot for use in information transmission from the mobile station to the base station is called as an up link slot.
FIG. 1 illustrates an architecture of down link slots and up link slots of a bidirectional communication in a related art mobile communication system.
Referring to FIG. 1, data frames are transmitted in a forward or backward direction during time slots S1xcx9cS4 assigned in advance. That is, the data frames are transmitted between the mobile station and the base station continuously alternating the down link slot S1 and S3 and the up link slots S2 and S4. That is, the data frames produced at the base station or the mobile station are transmitted repeatedly alternating assigned down link slots and up link slots. This type of signal transmission has been developed on the assumption that the mobile communication network serves for a speech data transmission in which a ratio of data transmission between a transmission side and a reception side is 1:1. Due to this reason, a trend is kept on, in which the down link slots and the up link slots are assigned simply at an equal ratio to most of current mobile communication devices. However, in a mobile communication service of IMT-2000 communication network basis, not only speech services, but also a variety of multimedia services, such as internet service and image broadcasting service are provided. In the internet or image service, an asymmetric transmission system is employed, in which an amount of data is transmitted in down link slots is relatively greater than an amount of data transmitted in up link slots, resulting to use slots of one direction of the down or up link slots continuously while slots of the other direction are almost not used in a case the multimedia service is given using a communication network having the down link slots and the up link slots are assigned equally. In such as case, there is a problem that a capacity of a given channel is not used effectively. Consequently, to match to such an asymmetric transmission system, a TDD(Time Division Duplex) system is suggested, in which different numbers of down link slots and up link slots are assigned. That is, numbers of down link slots and up link slots are varied with amounts of data.
However, the TDD system has many problems in practical applications. The greatest problems are that random access and synchronization acquisition are difficult because periods of the mobile station and the base station which have regular down link slots and up link slots are not known in advance when the mobile station attempts to start an initial communication. In order to solve such problems, as shown in FIG. 2, an improved TDD system is suggested, which employs both a static period(TDD1) having down link slots and up links slots assigned therein in a regular alternation and a dynamic period(TDD2) having down link slots and up links slots irregularly assigned therein according to amount of the data to be transmitted. In the improved TDD system, the problems of random access and the synchronization acquisition between the mobile station and the base station can be solved with easy by using the static period(TDD1). And, since a communication can be made by providing numbers of down link slots and up link slots in the dynamic period(TDD2) varied with an amount of data, a given channel capacity can be used, effectively.
Thus, the static period(TDD1) in which the down link slots and the up link slots are assigned alternatively is provided for solving the problems in random access and synchronization. However, there are no suggestions on standards or techniques which improve an efficiency of given channel capacity in cases when numerous subscribers require calls or hand-off almost at a time in a city center where many offices are concentrated or a business quarter where many people gather. Therefore, there is no appropriate way to solve the problem when a number of call or hand-off required on the same time exceeds the given channel capacity. Accordingly, a technique in need, which can maximize an efficiency of a given channel source in a case when there is an excessive number of call or hand-off requirements in the IMT-2000 communication network in which the multimedia service is provided.
Accordingly, the present invention is directed to a method of communication between a mobile station and a base station in a mobile communication system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method of communication between a mobile station and a base station in a mobile communication system of IMT-2000 communication network which can provide a variety of communication services, which allows an effective communication between mobile stations and a base station when numerous mobile stations require communication services at almost a time.
Another object of the present invention is to provide a method of communication between a mobile station and a base station in a mobile communication system of IMT-2000 communication network which can provide a variety of communication services, which can provide a data frame structure that allows easy determination of transmission system depending on characteristic and amount of data to be transmitted when numerous mobile stations require communication services almost at a time.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the method of communication between a mobile station and a base station in a mobile communication system of IMT-2000 communication network basis, which is suitable for effective transmission of various multimedia information within a given channel capacity, the method including the steps of (1) when a mobile station receives a data transmission request, providing one portion of a period of a data frame with regular number and arrangement of down link slots and up link slots and the other portion of the data frame with irregular number and arrangement of down link slots or/and up link slots depending on characteristics and amount of subscriber data to be transmitted, (2) determining a transmission type according to which a communication is executed using a competition period for determining priorities of the subscriber data, a reservation period for making a reservation for time slots for use in transmission of the subscriber data, and an assignment period for assigning a memory period according to an amount of the subscriber data, which periods are selectively and respectively included in the one portion of the data frame and in the other portion of the data frame, and (3) providing the data frame according to the transmission type and transmitting to the base station.
In another aspect of the present invention, there is provided a structure of a data frame for use in communication between a mobile station and a base station in a mobile communication system, the data frame having a static period having at least one or more than down link slots and at least one or more than one up link slots, both assigned thereto regularly and alternatively and a dynamic period having down link slots and up link slots, both assigned thereto irregularly, the structure including a competition period for determining a priority of data to be transmitted from the mobile or the base station during each of the static period or the dynamic period, a reservation period for making a reservation for a slot for use in transmission of the data, an assignment period for assigning a memory period according to an amount of the data, wherein the competition period, the reservation period and the assignment period are provided selectively.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.